1. Field of the Invention
The present invention relates to a method for fixing a ring of a sound-absorbing material on the circumferential area of a rim facing the interior of a tire mounted on the rim. The invention relates further to a motor vehicle wheel with a tire mounted on a rim in whose interior, encircling the rim, is positioned a ring made of a sound-absorbing material.
2. Discussion of Background Information
The tire vibrations produced during the rolling of the tire are known to be the main cause of the noise emitted by motor vehicles that is experienced as disturbing. In particular, the acoustic power produced in the tire torus is very high, with the acoustic oscillations created here being partially transferred via vehicle parts into the vehicle cabin and partially being radiated outward via the tire sidewalls. It is known that the incorporation of sound-absorbing materials into the tire interior reduces the acoustic power that is radiated.
Known, for instance, from German Patent No. DE 29 46 273 C2 is a device for reducing the tire noise of motor vehicles in which sound-absorbing and open-pore components are provided at the rim which extend into the interior of the tire without any contact with the interior tire surface.
The solution known from DE 44 00 912 A is concerned with realizing an effective reduction of the sound waves developing in the torus area, while taking into consideration an easy way of mounting and demounting. It is suggested here to introduce the sound-insulating material into a flexible hose which, due to its flexibility, can be mounted together with the tire onto the rim. The embodiment in the form of a hose includes the advantage of easy mounting. At higher speeds, in which the centrifugal forces that occur are already large, the comparatively loose fit of this assembly at the rim and its weight are disadvantageous.
From the German Patent DE 30 42 350 C2 a pneumatic vehicle tire is also known whose interior surfaces are partially or entirely covered with a sound-reducing coating of an open-pored foam. In order to achieve effective damping of the structure-borne noise in the frequency ranges that are particularly important physiologically, it is suggested here to use a special cross-linked polyurethane foam in a certain layer thickness that damps structure-borne noise.
Open-pore foam is particularly well suited by nature to lower the airborne sound level in the tire interior. One skilled in the art knows a number of foam materials that are well suited to individual requirements. In choosing the appropriate foam material, attention must be paid to a high level of sound absorption even at low frequencies. Furthermore, it is known that other materials also can be used for a sound absorption inside of a tire, for instance, sound-damping installations consisting of cotton, wool, felt, or other similar materials.
At higher speeds, in particular, the resistance to centrifugal forces of sound-insulating installations in the tire interiors is particularly important. The known solutions are not satisfying in that respect since the influence of centrifugal forces, in particular at higher speeds, causes undesired changes to occur in the sound-absorption characteristics due to deformations occurring in the material as well as due to changes in the cross-section of the installations. The sound absorbing material should therefore be as light in weight as possible.
An aspect of the invention is to provide a solution for the fixing or mounting of a sound-absorbing installation at the rim, comprising in particular of foam material, which ensures the desired resistance to centrifugal forces with practically no increase, or only an insignificant increase, in weight of the sound-reducing installation.
This aspect is obtained in the process according to the invention in that the ring of sound absorbing material is covered by threads which are stretched alongside the ring towards or onto the rim.
In relation to the motor vehicle wheel according to the invention, this aspect is obtained in that the ring of sound-absorbing material is fixed to the rim via threads covering it that are stretched on both sides of the ring towards or onto the rim.
The treads covering the sound-insulating installation in the tire effectively prevent undesired and/or negative deformations of the sound-absorbing material and are simultaneously capable of holding the sound absorbing installation in its position at the rim, even at high speeds. The invention also makes it possible to fix sound absorbing installations of different cross-sectional shapes to the rim.
It is advantageous for ensuring good resistance to centrifugal forces if the threads are directed in at least essentially radial and axial direction or, in relation to the circumferential direction of the rim, up to a diagonal direction.
According to a preferred embodiment of the invention these threads are the woof threads of a web or a web-like structure which is provided at each of its borders with at least one warp thread. Such a simple construction is quite sufficient to fix the sound-absorbing ring to the rim in a manner that is resistant to centrifugal forces.
In this embodiment, in particular, the fixing can take a particularly simple form in that the warp threads are mounting threads that can be pulled tight, in particular made of plastic or steel.
There are a multitude of possibilities for connecting the corresponding ends of the mounting threads to one another, in particular, tying, gluing, pressing, fusing, or sewing.
In order to prevent the sound absorbing ring from shifting it is usually sufficient when the mounting threads are prevented from slipping out of their position at the rim.
A simple possibility for preventing shifting is the provision of strips, moldings, or the like made of rubber or plastic at the rim where the mounting threads are stretched. Alternately, grooves can be provided at the rim which are meant to hold the mounting threads.
In another embodiment of the invention the mounting threads themselves can be made slip resistant, in particular rubberized.
In another variant of an embodiment of the invention the sound absorbing threads spanning the ring are clamped to the rim on both sides of the ring. This is also a version of the embodiment that can be handled relatively simply.
In order to facilitate the clamping of the threads they can be held by edge strips or the like, made, in particular, of rubber. In this case it is advantageous to clamp the edge strip on both sides of the sound-absorbing ring to the rim.
Again it is advantageous in this embodiment to provide additional measures against an unintentional slipping. To this end, the threads or the edge strips can be clamped to rubber moldings connected to the rim. As an additional measure to prevent slipping, these rubber moldings can be provided with circular grooves in which the clamping of the edge strips or the threads occurs.
The clamping itself can be accomplished in a simple manner by clamps such as stretchable tapes or the like.
In all variant embodiments the web or formation can be provided with additional threads spanning in the circumferential direction in order to facilitate handling thereof.
In an additional measure to facilitate handling, provision is made to glue the threads and/or the formation containing them to the sound absorbing ring before it is mounted onto the rim.
In another embodiment of the invention the threads spanning the ring are parts of a compact but acoustically transparent web.
In this case separate clamps can be omitted in that the web is stretched towards the rim or onto the rim by means of shrinkable threads, especially threads that shrink as a result of wetting. This simplifies handling, since separate attachment of the web to the rim is no longer necessary.
In a preferred embodiment the shrinkable threads can be woven in, at least in the edge strips of the web, where they are interwoven in the circumferential direction.
In an alternative form of the embodiment, provision is made for the shrinkable threads to be positioned in pockets of the web formed at the edges running in the circumferential direction. In an embodiment with interwoven shrinkable threads the production of the web is somewhat more expensive, and in the second embodiment the expense for the production of the pockets and later positioning of the threads in webs of simple design is even greater.
In another alternative embodiment of the web provision can be made for the web itself to be formed, at least in part, of shrinkable threads. Here, the entire web can be produced of shrinkable threads as well.
The handling of a web made of shrinkable threads is especially simple when, in particular, the web is mounted in a prefabbed ringlike closed form onto the sound-absorbing ring positioned on the rim.
An example for suitable material for the shrinkable rim is threads of PVA.
According to a particularly preferred embodiment of the invention the sound-absorbing ring is an open-pore foam ring. Foam is particularly well suited due to both its sound absorbing characteristics and its weight.
According to an aspect of the present invention, a method is provided for fixing a ring of sound-absorbing material to a rim of a wheel, the rim having a circumferential area facing an interior of a tire mounted on the rim. The method includes positioning a ring of sound-absorbing material onto the circumferential area of the rim; and stretching threads over the ring of sound-absorbing material one of toward and onto the rim.
According to another aspect of the invention, the threads are stretched over both sides of the ring, whereby the ring is held onto the rim by the threads. In yet another aspect of the invention, the threads are configured in a crossing pattern in a substantially perpendicular and substantially parallel orientation with respect to the circumferential direction of the rim. In another aspect of the present invention. In another aspect of the present invention, the threads are configured in a diagonally crossing orientation with respect the circumferential direction of the rim.
According to a further aspect of the present invention, a motor vehicle wheel having a tire mounted on a rim is provided. A ring made of a sound-absorbing material positioned inside the interior of the tire and encircling the rim; and threads arranged to cover the ring to fix the ring to the rim; wherein the threads are stretched over both sides of the ring one of towards or onto the rim.
In another aspect of the invention, the threads are configured in a crossing pattern to be oriented substantially perpendicular to and substantially parallel to the circumferential direction of the rim. According to still another aspect of the invention, the threads are configured in a diagonally crossing orientation with respect the circumferential direction of the rim. In another aspect of the invention, the threads form a web having a pair of edge areas, the web being formed to cover an exterior surface of the ring.
Other aspects of the invention include, the web having woof threads and at least one warp thread oriented in a circumferential direction in the area of each of the pair of edge areas. Further aspects of the invention include at least one warp thread being made of plastic or steel. According to other aspects of the invention, the at least one warp thread includes at least one mounting thread that can be pulled tight. According to another aspect of the invention, the at least one mounting thread is slip resistant.
According to a further aspect of the present invention, the at least one mounting thread is rubberized. According to a still further aspect of the invention, the rim is provided with grooves for accommodating the at least one mounting thread. According to another aspect of the invention, the at least one mounting thread is secured against slipping from its mounting position on the rim. In yet another aspect of the present invention, corresponding ends of the at least one mounting thread are connected with one another by at least one of tying, gluing, pressing, fusing and sewing.
Additionally, other aspects include additional threads, running in the circumferential direction of the rim, are interwoven into said web with said threads. Other aspects include the threads or the web containing the threads, are glued to the ring before the ring is mounted on the rim. In another aspect of the present invention, the web is compact and transparent. According to a further aspect of the present invention, the web is stretched one of toward or onto the rim by shrinkable threads.
In another aspect of the present invention, the shrinkable threads are positioned in pockets formed in the edge ,area of the web. According to a further aspect of the present invention, the shrinkable threads are interwoven into the edge areas of the web at least in the circumferential direction of the rim. In another aspect of the present invention, the shrinkable threads shrink upon exposure to moisture.
According to a still further aspect of the present invention, the shrinkable threads are made of PVA. In another aspect of the present invention, threads other than said shrinkable threads are made of one of nylon, rayon, polyester and aramid. According to a different aspect, the web is formed at least partially of shrinkable threads.
According to another aspect of the present invention, the web is positioned in a closed ring shape on the ring positioned on the rim. Further aspects of the invention include wherein one of resilient strips and moldings are used to mount the threads to the rim. Other aspects include, wherein the threads drawn along both sides of the ring are clamped tight onto the rim. According to other aspects of the present invention; the threads are held in resilient edge strips located on the rim. According to another aspect of the invention, the edge strips are made of rubber.
According to a further aspect of the invention, the edge strips are located on both sides of the rim. According to a still further aspect of the invention, at least one of the threads or the edge strips are clamped onto rubber moldings which are connected to the rim. According to another aspect of the invention, the at least one of the threads or the edge strips are glued onto the rubber moldings which are connected to the rim.
In yet another aspect of the invention, the strips and the moldings are made of one of plastic and rubber. According to another aspect of the present invention, the rubber moldings are provided with circumferential grooves. In yet another aspect of the present invention, the threads or the edge strips are clamped in grooves formed on the rim. In another aspect of the present invention, the threads or the edge strips are clamped to the rim via at least one clamping device. According to still a further aspect of the present invention, the at least one clamping device includes stretchable tape.
In another aspect of the invention, the ring is an open pore foam ring. According to a still further aspect of the invention, the ring has a substantially oval or substantially semicircular cross-section. According to a further aspect of the invention, the ring, in the area where it interfaces the rim, is formed to the corresponding profile of the rim.
Further aspects of the invention include, a sound-absorbing device for a motor vehicle wheel having a tire mounted on a rim. The device includes a ring made of a sound-absorbing material positioned inside the interior of the tire and encircling the rim. The ring is adapted to be fixed to the rim via threads covering the ring that are at least one of stretched, drawn and tightened over and both sides of the ring towards or onto the rim.